This invention relates to a controller for a water softener. More specifically, it relates to a controller for a water softener that reduces the amount of resin that must be held in reserve prior to regeneration of the unit.
Electronic controllers have recently become very inexpensive and readily available for use in common household items. They are now regularly used for a number of appliances, including water softeners. While treating hard water, an ion exchange resin in a water softener absorbs calcium and magnesium ions from the water and replaces them with sodium ions. The resin becomes ineffective when the amount of available sodium is depleted and the resin is saturated with calcium and magnesium, and must periodically be regenerated. Water treatment is then suspended while the resin is regenerated in a multi-step process to flush the calcium and magnesium ions from the resin and restore the sodium level. The resin is first backwashed, by reversing the flow of the incoming water, to remove sediment. Next, the resin bed is contacted with a brine solution, whereby the resin takes sodium ions from the high concentration solution and displaces the calcium and magnesium ions into the brine. When an optimum amount of ion exchange has taken place, the brine solution and the unwanted hard water ions in it are discharged from the resin bed. After being rinsed to remove residual brine, the restored resin bed is then returned to service treating hard water.
Water softeners use electronic controllers to direct the timing and the opening and closing of valves during the various process steps. Some newer, more sophisticated water softeners use electronics to schedule the next regeneration cycle based on one or more inputs. The input data includes information from timers, flow meters, stored historical data on water usage and the like.
In U.S. Pat. No. 6,235,200 to Mace, a controller is disclosed for regeneration of a water conditioner. The apparatus measures water usage over a predetermined time period, and electronically stores the water usage data. Information for the same time period is averaged with similar time slots, such as the same time for previous days, or the same time period for previous weeks. The controller thereby determines time slots during which there is no water usage or when water usage is minimized. When resin saturation reaches a predetermined level, the controller determines the next regeneration time based upon historical water usage during given time periods. Actual current water usage is not used to determine appropriate regeneration periods.
A water softener controller with a microprocessor is described in U.S. Pat. No. 4,490,249 to Seal. Water usage is measured by a flow meter. Based on the flow meter data, the microprocessor determines the amount of water used since the last regeneration, and also keeps a running average of daily average soft water consumption. At a prescribed regeneration time, the microprocessor calculates the remaining resin capacity, and regeneration is initiated if the resin capacity is less than that necessary to supply the next full day""s supply of soft water. Regeneration always takes place at the prescribed time of day.
The regeneration scheme used in Zabinski, U.S. Pat. No. 5,751,598, is very similar to that of Seal. Here the regeneration system is armed using information from a flow meter, a timer or electrodes that detect the impedance of the solution. Once armed, regeneration starts at the next predetermined regeneration time.
Regeneration in a multiple tank treatment system is described in U.S. Pat. No. 5,069,779 to Brown. A controller initiates regeneration of the tank currently in use when the resin in that tank reaches a predetermined saturation level. The controller also anticipates saturation of other tanks, and may regenerate the current tank early if it determines that another tank will become saturated before regeneration of the current tank is complete. Current water usage is not a concern with this system since there is a constant supply of soft water from the tanks that are not regenerating.
Schreiner, in U.S. Pat. No. 5,879,559, also teaches the combination of a mechanical clock and an electronic controller to operate a drive motor having an output shaft coupled to a valve system. A switch set by the mechanical clock, and an electronic ready signal must both be present for regeneration to occur. The ready signal is generated by a timed signal, such as the day of the week, or from a demand regeneration scheme. The demand signal is produced with input from a flow meter when water flow has exceeded a set value. Immediate regeneration may be initiated by the push of a button by the user.
All of these schemes use the electronic controllers to schedule regeneration some time in the future once some level of saturation of the resin is obtained. Because the controller schedules the regeneration to occur in the future, regeneration must be scheduled while there is sufficient resin to provide soft water during the time between the time regeneration is scheduled and the time that regeneration actually begins. If a timer initiates regeneration no more than once daily, then the reserve resin provided should be no less than that needed to provide treated water for 24 hours. The resin that is held in reserve is not used efficiently. Theoretically, it is possible that this resin will never be used to soften water. Therefore, the unit has to have resin in reserve that is rarely, if ever, used to soften water.
Withholding a portion of the resin in reserve leads to excessive salt and water usage during regeneration. Brine usage is determined based on complete saturation of the resin. If up to one third of the resin bed has not been saturated with calcium ions, the amount of brine required to regenerate could be reduced by a corresponding amount. However, because the exact saturation level of the bed is unknown, the brine usage assumes total resin saturation.
Another problem with water softeners is finding a predetermined time to regenerate when there is no current demand for soft water. Users frequently program the controller to initiate the regeneration cycle when household members are usually sleeping, for example at 2:00AM. This schedule limits initiation of regeneration to once a day, requiring that the reserve of useable resin be sufficient to meet soft water demand for at least 24 hours. Such a rigid schedule of regeneration also fails to account for unusual circumstances by the soft water users, such as when a household member desires to shower after arriving home very late at night.
None of the prior art provides for monitoring of the current water usage for the purpose of determining if regeneration should be delayed due to current soft water demand. Prior control sequences have used historical determinations as to when water usage is nil or minimized. However, none have determined that regeneration is due, then started monitoring current water usage to determine when there is no present soft water demand.
It is therefore an object of this invention to provide an improved controller for a water softener that delays regeneration if there is a current demand for soft water.
It is another object of this invention to provide an improved controller for a water softener that minimizes the amount of resin that must be kept on reserve.
It is still another object of this invention to provide an improved controller for a water softener that provides a fully automatic setting for the controller, minimizing the amount of input required from the consumer.
It is yet another object of this invention to provide an improved control sequence for a water softener that is more economical and environmentally friendly due to lower water and salt usage.
These and other objects are met or exceeded by the present invention, which features a controller for a water softener that does not delay regeneration to a preselected time of day.
More specifically, the present invention provides a controller for a water softener. The water softener has an ion exchange resin capable of receiving hard water ions from hard water during a softening step and releasing the hard water ions during a regeneration step. The controller includes a processor programmed to cause termination of the softening step and initiate the regeneration step when both a first and a second condition are met. When the resin is saturated with hard water ions, the first condition is met. The second condition is met when current demand for water is at or below a predetermined flow rate.
The water softener and controller of the present invention minimizes the inventory of reserve resin by not calling for regeneration until the bed is substantially saturated. Full use of the resin reduces the amount of resin that is needed to treat a constant volume of water. When smaller quantities of resin are required, the housing can be made smaller since the compartments for storing the resin and for storing salt can both be reduced in size and still obtain the same performance. Compact units are more easily designed for use in small homes or apartments.
When the resin is used more fully, regeneration needs to occur less frequently compared to controllers that utilize an average amount of reserve resin. Resin is held in reserve because regeneration is primarily controlled by time. At a prescribed time, regeneration begins regardless of the saturation of the remaining resin. If 20% of the resin is consistently not used in a unit that regenerates daily, an extra regeneration is required every 4 days. Sufficient salt and water are used to regenerate the entire bed, even though the reserve resin does not need regeneration. Extra water and salt usage makes operation of the softener more expensive for the user and puts a strain on the environment.
The controller of the instant invention also makes it easier for a novice or disinterested user to efficiently use his softener. One with no experience in the operation of a water softener may have no idea when or how to schedule regeneration of the unit. With the controller of this invention, the user need only answer a few questions programmed into the controller to be assured that the unit will regenerate as needed but still minimize use of water and salt.